Various types of investigations of samples, e.g., biological samples, require spatial separation of different macromolecules of the sample from one another. This is typically conducted by applying to the sample an electrophoresis process in which different molecules are separated due to their different molecular weights.
FIG. 1 schematically illustrates the principles of this conventional technique utilizing a gel electrophoresis system 1. The system 1 includes a container 3 in which the separation process takes place, and a voltage supply assembly 5. Container 3 is filled with an appropriate matrix medium 7, typically gel, e.g., polysaccharide such as Agarose. Several dozes of the same sample 9 (or different samples, as the case may be), composed of different molecules to be separated, are inserted into specific holes (wells) 11 in the gel medium 7. The molecules of the sample 9 may be naturally charged, charge may be applied prior to electrophoresis, or an additional ionic buffer serving as a separating agent may be added to the gel medium 7. Then, the voltage supply assembly 5 is operated to apply an electric potential (voltage difference) across the gel medium 7. The gel medium 7 acts as a sieving matrix to assist in retarding and separating the individual molecules as they migrate under the electric potential. The electric potential is typically applied for a certain fixed time period, during which the lighter molecules move more quickly, and at the end of this time period, the lighter molecules thus moved farther than heavier molecules.
In order to identify the results of the separation process, specific substances (markers) are typically applied to the sample 9 prior to the application of the electric potential. Such markers include for example fluorescent or chemiluscent materials, which are tied to specific molecules in the sample 9. After the application of electric potential is ceased, an exposure process commences to thereby image the sample and identify the molecules contained therein. This is typically carried out in a separate system (in ‘dark’ room), to which the sample is transferred from the separation system. During the imaging process, the separation results (gel 7 with the rest of the sample material in it) are ‘exposed’ to predetermined radiation, thus enabling visualization of the separation results. In a case of fluorescents dyes, this procedure includes application of UV illumination and consequent imaging of the gel medium 7. Once the image is ready, analysis can commence, for example aimed at identifying the molecules and determining their amount in the sample 9.
U.S. Pat. No. 5,055,172 discloses an electrophoresis system, which separates charged chemical substances by means of applying an electrical potential across a buffer solution which includes those chemical substances. The system includes a power supply and control system which has a wide dynamic range of constant voltage, current and power which may be supplied. The power supply includes a flyback topology and a control system which allows an operator to specify a wide range of constant voltage, current or power supply requirements for the electrophoresis system.
U.S. Pat. No. 5,976,338 discloses a DNA analyzer that comprises a pair of temperature control units on both sides of gel and a light-transmitting slit on one of the elements. Irradiation of an excitation beam over the gel and signal detection are practiced through the slit. By introducing dry air onto the slit part, mildew occurrence is prevented on the detecting part. The power level applied to the gel is detected, and the temperature of the temperature control units is calculated, so that the gel temperature might be a predetermined temperature. On the basis of the detected power level, the feedback control of the power level is thereafter carried out. The gel temperature can be controlled appropriately and strictly during electrophoresis in an automatic fluorescent electrophoresis system, so that high-speed analysis can be done highly reproducibly at a higher voltage applied even by SSCP.